clang -dumpversion returns 4.2.1 for legacy reason, update it

[sylvestre.ledru]

Summary

It has been introduced in 2011 for gcc compat:
https://github.com/llvm-mirror/clang/commit/95a907fc0f2f717dca38a379c1d2353bfea06d4f
it is probably time to remove it to remove the confusion.

reported: https://bugs.llvm.org/show_bug.cgi?id=38836
https://bugs.launchpad.net/ubuntu/+source/llvm-defaults/+bug/1810860

[sylvestre.ledru]

@ddunbar is that ok with you? Thanks
See
https://bugs.llvm.org/show_bug.cgi?id=38836
https://bugs.launchpad.net/ubuntu/+source/llvm-defaults/+bug/1810860

[sylvestre.ledru]

ping?

[sylvestre.ledru]

@ddunbar ping?

[rnk]

Code lgtm, with a suggestion to tighten the test.

lib/Driver/Driver.cpp

1631

We really ought to reconsider __VERSION__ as well, although I don't think anyone checks that. Today I get this for it:

"4.2.1 Compatible Clang 9.0.0 ([e-mail]:llvm/llvm-project.git bd6354105b055af6193fb2b7561fe6f5ae0eb0d8)"

test/Driver/immediate-options.c

10

Maybe check {{[0-9]+\.[0-9.]+}}, to insist that it's a sequence of numbers and dots.

[sylvestre.ledru]

Improve the test (thanks rnk)

[sylvestre.ledru]

@rnk btw, do you think it should be added to the clang release notes?

lib/Driver/Driver.cpp

1631

I can have a look to that if you want

[sylvestre.ledru]

Remove the empty directories

[rnk]

In D56803#1441876, @sylvestre.ledru wrote:

@rnk btw, do you think it should be added to the clang release notes?

I think it is release-note worthy. If you change VERSION, you can mention that as well.

lib/Driver/Driver.cpp

1631

If you're feeling motivated, I think it's worth doing to try to get us into a more consistent state.

lib/Driver/Driver.cpp

bool Driver::HandleImmediateArgs(const Compilation &C) {
   if (C.getArgs().hasArg(options::OPT_dumpmachine)) {
     llvm::outs() << C.getDefaultToolChain().getTripleString() << '\n';
     return false;
   }
 
   if (C.getArgs().hasArg(options::OPT_dumpversion)) {
     // Since -dumpversion is only implemented for pedantic GCC compatibility, we
     // return an answer which matches our definition of __VERSION__.
-    //
-    // If we want to return a more correct answer some day, then we should
-    // introduce a non-pedantically GCC compatible mode to Clang in which we
-    // provide sensible definitions for -dumpversion, __VERSION__, etc.
-    llvm::outs() << "4.2.1\n";
+    llvm::outs() << CLANG_VERSION_STRING << "\n";
     return false;
   }
 
   if (C.getArgs().hasArg(options::OPT__print_diagnostic_categories)) {
     PrintDiagnosticCategories(llvm::outs());
     return false;
   }
 

test/Driver/immediate-options.c

 // RUN: %clang --help | FileCheck %s -check-prefix=HELP
 // HELP: isystem
 // HELP-NOT: ast-dump
 // HELP-NOT: driver-mode
 
 // RUN: %clang --help-hidden | FileCheck %s -check-prefix=HELP-HIDDEN
 // HELP-HIDDEN: driver-mode
 
 // RUN: %clang -dumpversion | FileCheck %s -check-prefix=DUMPVERSION
-// DUMPVERSION: 4.2.1
+// DUMPVERSION: {{[0-9]+\.[0-9]+.*}}
 
 // RUN: %clang -print-search-dirs | FileCheck %s -check-prefix=PRINT-SEARCH-DIRS
 // PRINT-SEARCH-DIRS: programs: ={{.*}}
 // PRINT-SEARCH-DIRS: libraries: ={{.*}}
 
 // Test if the -print-resource-dir option is accepted without error.
 // Allow unspecified output because the value of CLANG_RESOURCE_DIR is unknown.
 // RUN: %clang -print-resource-dir | FileCheck %s -check-prefix=PRINT-RESOURCE-DIR
 // PRINT-RESOURCE-DIR: {{.+}}